U.S. patent number 7,448,761 [Application Number 11/266,169] was granted by the patent office on 2008-11-11 for architecture for a projector.
This patent grant is currently assigned to BARCO, naamloze vennootschap. Invention is credited to Nico Coulier, Peter Gerets, Stefan Lesschaeve, Krist Jacques Vandorpe.
United States Patent |
7,448,761 |
Lesschaeve , et al. |
November 11, 2008 |
Architecture for a projector
Abstract
An improved architecture for a projector comprising a light
source in the form of a lamp with a curved reflector with a
distinctive focal distance for converging the light beam of the
lamp; a so called cold mirror; an integration rod; a relay optics
system consisting of a plurality of lenses followed by a light
valve, wherein the architecture allows for the use of light sources
with different focal distances.
Inventors: |
Lesschaeve; Stefan
(Oudernaarde, BE), Vandorpe; Krist Jacques
(Beveren-Leie, BE), Coulier; Nico (Zulte,
BE), Gerets; Peter (Roeselare, BE) |
Assignee: |
BARCO, naamloze vennootschap
(Kortrijk, BE)
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Family
ID: |
36036185 |
Appl.
No.: |
11/266,169 |
Filed: |
November 4, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060114429 A1 |
Jun 1, 2006 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60631431 |
Nov 30, 2004 |
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Current U.S.
Class: |
353/102; 349/62;
353/87; 353/98; 362/560 |
Current CPC
Class: |
G02B
27/0994 (20130101); G03B 21/28 (20130101); G02B
19/0004 (20130101); G02B 19/0047 (20130101); G03B
21/16 (20130101); G03B 21/2066 (20130101) |
Current International
Class: |
G03B
21/20 (20060101); G02F 1/13357 (20060101); G03B
21/14 (20060101) |
Field of
Search: |
;353/20,33,37,85-87,100-102,98 ;349/61-62,67 ;362/559-561 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102 56 506 |
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Jul 2004 |
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DE |
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934650 |
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Aug 1963 |
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GB |
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WO 03/021296 |
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Mar 2003 |
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WO |
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Other References
Patent Abstracts of Japan, vol. 1996, No. 09, Sep. 30, 1996 &
JP 08 124841 A (Cannon Inc), May 17, 1996, abstract. cited by other
.
Patent Abstracts of Japan, vol. 1995, No. 03, Apr. 28, 1995 &
JP 06 331982 A (Fujitsu General Ltd), Dec. 2, 1994, abstract. cited
by other.
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Primary Examiner: Sever; Andrew T
Attorney, Agent or Firm: Bacon & Thomas, PLLC
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
The benefit of Provisional Application No. 60/631,431 filed Nov.
30, 2004 is claimed, and the entirety of said provisional
application is incorporated herein by reference.
Claims
The invention claimed is:
1. An architecture for a projector comprising a light source in the
form of a lamp with a curved reflector with a distinctive focal
distance for converging the light beam of the lamp; an integration
rod; a cold mirror disposed between the light source and the
integration rod; and a relay optics system comprising a plurality
of lenses followed by a light valve and a condenser system disposed
between the light source and the cold mirror, which condenser
system is located at a distance from the light source and wherein
the condenser system is adapted for converging the light beam of
the light source in such a way that the focal point of the
converging light beam which is reflected on the cold mirror is
located at or in the vicinity of the entrance of the integration
rod, wherein the architecture enables the use of light sources with
different focal distances and wherein the condenser system
comprises two concentrically aligned bi-convex lenses.
2. The architecture according to claim 1, wherein the condenser
system comprises two identical lenses.
3. The architecture to claim 1, wherein for each of the light
sources that can be used in the projector, a condenser system is
provided which is arranged so that when using this particular
condenser in combination with the corresponding light source, the
light source is positioned at a fixed spot in the projector at a
predetermined distance from the cold mirror.
4. The architecture according to claim 1, wherein an ultraviolet
filter is provided between the light source and the condenser
system.
5. The architecture according to claim 4, wherein the condenser
system comprises a plurality of lenses and where the ultraviolet
filter is provided as a ultraviolet reflective coating applied on
the lens nearest the light source.
6. The architecture according to claim 1, wherein the integration
rod is made of fused silica.
7. The architecture according to claim 1, wherein a lens is
provided between the integration rod and the cold mirror, which
lens is made of fused silica.
8. A projector with the architecture according to claim 1.
9. An architecture for a projector, comprising light source in the
form of a lamp with a curved reflector with a distinctive focal
distance for converging the light beam of the lamp; an integration
rod which is placed after the light source with its entrance
located at or near the focal point of the light source; a cold
mirror which is positioned behind the exit of the integration rod;
a relay optics system comprising a plurality of lenses followed by
a light valve, wherein the architecture enables the use of light
sources with different focal distances and wherein the position of
the light source relative to the integration rod is adjustable so
as to enable the focal point of different light sources having
different focal distances to be located at or near the entrance of
the integration rod.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved architecture for a
projector, in particular for a projector used for displaying images
on a screen.
2. Discussion of the Related Art
The present invention relates to an architecture for a projector
comprising a light source in the form a lamp, for example a xenon
lamp, with a curved reflector with a distinctive focal number and
focal distance for converging the light beam of the lamp; a so
called cold mirror which reflects the visual light and transmits
the infrared light; an integration rod; a relay optics system
consisting of a plurality of lenses and a light valve such as a
digital mirror device (DMD), a liquid crystal display (LCD), an
LCOS or the like.
The architecture of known projectors is such that the cold mirror
is placed in between the light source and the integration rod and
that the entrance of the integration rod is at the focal point of
the light source.
A disadvantage of a projector with such a known architecture is
that it is suited for the use of only one kind of light source with
a particular focal number.
Indeed, replacing the light source by another light source with for
example a smaller focal number and repositioning the light source
so that the focal point of the light source would coincide with the
entrance of the integration rod, would result in a very small and
intense light spot on the cold mirror and would hence result in
locally damaging the cold mirror due to overheating and burning of
the cold mirror or the coatings of this cold mirror.
SUMMARY OF THE INVENTION
It is therefore an objective of the invention to provide for an
improved architecture of a projector which is not limited to the
use of only one type of light source.
To this end the present invention provides for an improved
architecture for a projector comprising a light source in the form
of a lamp with a curved reflector with a distinctive focal distance
for converging the light beam of the lamp; a so called cold mirror;
an integration rod; a relay optics system consisting of a plurality
of lenses followed by a light valve, wherein the architecture
allows for the use of light sources with different focal
distances.
An advantage of such an improved architecture is that one is not
limited to only one kind of light source and to one supplier, but
that one can choose amongst a larger number of light spots
available on the market.
According to a first preferred embodiment, the cold mirror is
situated between the light source and the integration rod and a
condenser system is provided between the light source and the cold
mirror at a distance from the light source which excels the focal
distance of the light source, the condenser system being adapted
for converging the light beam of the light source in such a way
that the focal point of the converging light beam which is
reflected on the cold mirror is located at or in the vicinity of
the entrance of the integration rod.
An advantage of such a preferred embodiment is that by using such a
condenser system, the light spot on the cold mirror can be made
sufficiently large in order to limit the intensity of the light
spot on the cold mirror and hence to avoid damage of the cold
mirror by overheating.
Such a condenser system can be realized in a relatively inexpensive
manner by two concentrically aligned bi-convex lenses.
Whenever a light source is replaced by another light source with a
different focal distance, the condenser system is also replaced by
a suitable condenser system which allows that the light source is
fitted at the same spot in the projector as the light source which
has to be replaced.
According to a second preferred embodiment the integration rod is
placed after the light source with its entrance located at or near
the focal point of the light source and the cold mirror is
positioned behind the exit of the integration rod.
An advantage of this second preferred embodiment is that the light
spot on the cold mirror is always nearly of the same size,
irrespective of the focal distance of the light source used, so
that when the light source is replaced by another light source with
the same intensity but with a different focal distance, there is no
risk that the light spot on the cold mirror becomes smaller and
more intense, which could result in damaging the cold mirror by
overheating.
The present invention also relates to a projector with an improved
architecture as described.
BRIEF DESCRIPTION OF THE DRAWINGS
With the intention of better showing the characteristics of the
invention, hereafter, as an example without any limitative
character, a number of preferred embodiments of a projector with
improved architecture according to the invention are described,
with reference to the accompanying drawings, wherein:
FIG. 1 schematically represents a prior art projector with known
architecture;
FIG. 2 represents a similar view as FIG. 1, but for a first
preferred embodiment of a projector with an improved architecture
according to the invention;
FIG. 3 represents a similar view as FIG. 2, but for a second
preferred embodiment of a projector according to the invention;
FIG. 4 represents the projector of FIG. 3, but with a different
light source.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The projector 1 represented in FIG. 1 is a prior art projector with
a known architecture, comprising a light source 2 with a converging
light beam 3, the light source 2 being composed of a lamp 4,
preferably a xenon bulb lamp, and a curved reflector 5 with a
particular focal point 6 of the converging light beam located at a
focal distance A from the light source 2.
The projector 1 further comprises an ultraviolet filter 7; a so
called cold mirror 8 which reflects the visual part 9 of the light
beam 3 and transmits the infrared part 10; an integration rod 11
with an entrance 12 for the reflected light beam 9 positioned at or
near the focal point 13 of the reflected light beam 9 and with an
exit 14 for the light beam 9; followed by a relay optics system 15
composed of a plurality of lenses 16, 17, 18, 19 and 20 of which,
in this case the lenses 17, 18, 19 and 20 are converging lenses;
and finally a light valve 21 such as a digital mirror device (DMD),
a liquid crystal display (LCD), an LCOS or the like, which serves
as a valve for altering the incoming light beam 9 for projection of
an image on a screen which is not represented in the figure.
The functioning of the projector 1 is as follows.
The converging light beam 3 which is generated by the light source
2 passes through the ultraviolet filter 7 and is projected on the
cold mirror 8 which reflects the visual part 9 of the light beam 3
and transmits the infrared part 10 which is then removed from the
optical path to protect the remaining optical elements 11, 16, 17,
18, 19, 20, 21 from heating.
The visual light beam 9 then passes the integration rod 11 and is
then optically altered by the relay optics in order to feed the
light valve 21 with an incoming light beam 9 with suitable
characteristics for use as projection light.
The light spot 22 which is created by the light beam 3 on the cold
mirror 8 is relatively large, so that the light energy is spread
over a relatively large area and hence the temperature of the cold
mirror stays reasonably low in order to avoid excessive heating of
the cold mirror 8, in particular of its coatings.
A known projector 1, as represented in FIG. 1, is typically
designed for a particular light source 2 with a particular focal
distance A which is usually defined by the focal number, which is
the ratio of the focal distance A to the diameter D of the
reflector 5 (f=A/D).
FIG. 2 represents a first preferred embodiment of a projector 23
with an architecture according to the invention, wherein a light
source 24 is used with a focal distance A' which is smaller than
the focal distance A of the light source 2 used in the projector 1
of FIG. 1.
This projector 23 according to the invention further comprises
similar optical elements as the projector 1 of FIG. 1, more
specifically a cold mirror 8, an integration rod 11, a relay optics
system 15 which is composed of a plurality of lenses 16, 17, 18, 19
and 20; and a light valve 21.
Additionally this projector 23 is equipped with a condenser system
25 fitted in the light beam 3 of the light source 24 between said
light source 24 and the cold mirror 8 and which is for example
composed of a pair of two identical and concentrically aligned
bi-convex lenses 26.
The condenser system 25 is provided at a distance B from the light
source 23 which is larger than the focal distance A' of the light
source 24 so that the light beam 3 generated by the light source 24
is convergent up to the focal point 27 of the light beam 3 and is
divergent past this focal point 27 up the condenser system 25.
The diverging light beam 3 is then transformed by the condenser
system 25 in a converging light beam which is projected on the cold
mirror 8 and partially reflected in the visual spectrum and further
focused up to the focal point 13 of the reflected light beam 9
situated at or in the vicinity of the entrance 12 of the
integration rod 11.
By using a condenser system 25, the spot 22 of the light beam 3 on
the cold mirror 8 can be larger than in case the light source 24
should be placed directly in front of the cold mirror 8 without
condenser system 26 and in a position such that the focal point 13
of the reflected light beam would coincide with the entrance 12 of
the integration rod 11.
This way damage to the cold mirror 8 or to the coatings of the cold
mirror 8 can be avoided.
The condenser system 25 is matched to the light source 24.
Whenever the light source 24 has to be replaced by a light source
with a different focal number, the condenser system 25 has to be
removed or replaced.
When the light source 24 has to be replaced by a light source 2 as
represented in FIG. 1, the condenser system 25 has to be removed,
whilst when the light source 24 has to be replaced by a light
source with a focal number different from that of the light sources
5 or 24, also the condenser system 25 has to be replaced by a
condenser system 25 matched to the focal number of the light source
to be fitted.
The condenser systems 25 matching with the different light sources
to be used are preferably so designed that the light sources are
always positioned at the same fixed spot in the projector 23 at a
predetermined distance from the cold mirror 8.
The condenser system 25 does not necessarily have to comprise two
lenses 26, but can also be made of only one lens or of a plurality
of superimposed lenses.
The relay optics system 15 can also be of a different architecture
than represented in the figures and comprise a different number and
type of lenses.
Optionally, an ultraviolet filter can be fitted in front of the
light source 24 between the light source and the condenser
system.
The ultraviolet filter can also be realized as an ultraviolet
reflective coating applied on the surface of the lens 26 nearest
the light source.
FIG. 3 represents a second preferred embodiment of a projector 28
with an improved architecture according to the invention.
The projector 28 is composed of similar components as the projector
1 of FIG. 1, in particular a light source 2, an ultraviolet filter
7, an integration rod 11 which is placed after the light source 2
with its entrance 12 located at or near the focal point 6 of the
light source 2, a relay optics system 15 composed of a plurality of
lenses 16, 17, 18, 19, 20, a light valve 21 and a cold mirror 8,
which, according to the invention, is positioned behind the
integration rod 11 at a distance from the exit 14, in particular in
this case after the first lens 16 of the relay optics system.
The integration rod and the first lens 16 are preferably made of
fused silica in order to be able to resist the high intensity of
infrared light.
Whenever the light source 2 is replaced by a light source 24 with a
different focal distance, the new light source 24 is positioned at
a distance from the entrance 12 of the integration rod 11 which is
equal, or approximately equal, to the focal distance A' of said
light source 24, as is represented in FIG. 4.
The projector 28 can be fitted with adjustable means to fix the
light source 24 at the appropriate focal distance from the
integration rod 11.
As can be appreciated from the comparison of FIGS. 3 and 4, the
area covered by the light spot 22 on the cold mirror 8 will be the
same in both cases, so that, using a light source 24 with a similar
light intensity as the light source 2 but with a different focal
number, the light intensity on the cold mirror 8 will be nearly the
same and hence there will be no risk of burning the cold mirror 8
when changing light sources.
From an optical point of view, it might be desirable to place the
cold mirror 8 directly after the integration rod 11 or integrated
in the relay optics system 15 with one or more of the lenses 16,
17, 18, 19 or 20 between integration rod 11 and the cold mirror
8.
The second preferred embodiment has the additional advantage over
the first preferred embodiment that it is compacter and more
efficient.
The present invention is in no way limited to the form of
embodiment described by way of an example and represented in the
figures, however, such an improved architecture for a projector
according to the invention can be realized in various forms without
leaving the scope of the invention.
* * * * *